Were Pterosaurs and Mosasaurs Dinosaurs?

In popular culture, you’ll often see the high flying Pteranodon and the ocean-going Mosasaurus referred to as “dinosaurs”. However, while both Pteranodon and Mosasaurus were both prehistoric reptiles, were they actually dinosaurs? Nope. Pterosaurs and mosasaurs (and other marine reptiles such as plesiosaurs) were worlds apart from dinosaurs, even if they existed during the same time and in the same places as the so-called “terrible lizards”.